The invention relates to a liquid crystal display, and more specifically to a polyimide liquid crystal display.
With advances in information and digitization, light, thin, and portable electronic products utilizing thin display panels have become popular. However, they are inconvenient for transport and complicated fabrication may cause low yield.
Thus, a transparent and flexible plastic substrate (0.1˜0.2 mm) has been developed. Such plastic substrate is thin, light, durable, and portable, and produced by a continuous rolling process, significantly reducing costs
Unfortunately, problems such as deposition of indium tin oxide (ITO) and thin film transistor (TFT) thereon and backend panel assembly occur. Additionally, the glass transition temperature (Tg) of the optical-level plastic substrate such as PET, PEN, PC, or m-COC (Arton or Zeonor) is lower than 200° C., unfavorable for fabrication. Also, PES substrate has insufficient solvent resistance, with yellowing and cracking at high temperatures (200° C.). Furthermore, some polyimide plastic substrates capable of thermal and solvent resistance, being dark brown, are only suitable for use in reflective LCD panels, not transmissive LCD panels.
Conventional extended polyimide has a lower coefficient of-thermal expansion (CTE) of about 20 ppm/° C., its retardation, however, is too large (Rth>1000 nm) for use in LCD panels.
Additionally, the plastic substrate must be fixed to a glass substrate by resin glue to facilitate subsequent multi-lithography and etching due to difficulty in handling. However, TFT element breakage and residual resin glue may easily occur when the plastic substrate is taken off the glass substrate.